The present invention relates to an image-forming apparatus that is mounted on, for example, an electrophotographic recording apparatus and a copying machine.
When a conventional electrophotographic recording apparatus such as a color electrophotographic recording apparatus is powered on, a fixing roller is heated so that the surface of the fixing roller reaches a predetermined temperature. Then, a carrier belt for transporting print paper is driven to run more than one complete round, so that a photoconductor, a charging roller, a developing roller and associated structural members rotate in an idling manner, while also receiving the same voltages as applied during printing. Then, the rotating structural members are stopped, so that the system enters a standby condition in which the recording apparatus waits for a print command. The idling rotation of the rotating structural members allows the toner in the developing section to be pre-charged triboelectrically.
With the conventional image-forming apparatus, immediately after a toner cartridge or a photoconductive drum has been replaced at the end of its lifetime, the fresh toner supplied to the photoconductor is not charged sufficiently yet. Therefore, the aforementioned normal idling rotation do not allow the toner to be charged sufficiently, resulting in poor print quality.
An object of the present invention is to provide an image-forming apparatus in which even when a toner cartridge or an image-forming unit is replaced, a good print quality is maintained.
An image forming apparatus has an image-forming unit in which a charging section and a developing section are rotated together with a photoconductor in an idling manner while also receiving voltages. The apparatus includes a sensor and a controller. The sensor outputs a detection signal indicating that the toner has been replenished in the image-forming unit. The controller controls the conditions of operation of the charging section, the developing section, and the photoconductor. The set of voltages, the set of speeds, and the time length are changed in accordance with the detection signal.
The detection signal may indicate an amount of toner in the image-forming unit, and the controller controls the voltages to change in accordance with the detection signal.
When the image-forming unit is nearly full of toner, the detection signal is equal to or higher than a first value and the controller sets the voltages to first voltage values. When the detection signal is lower than the first value, the controller sets the voltages to second voltage values lower than the first voltage values.
When the charging section, the developing section, and the photoconductor are rotating in the idling manner, the controller sets the voltages to first voltage values higher than third voltage values which are voltage values applied during printing.
When the image-forming unit is nearly empty of toner, the detection signal is equal to or less than a second value smaller than the first value. When the charging section, the developing section, and the photoconductor are rotating in the idling manner, the controller sets the voltages to fourth voltage values lower than the second voltage values.
The fourth voltage values are lower than the third voltage values.
The charging unit receives a voltage such that a surface of the photoconductor is charged by the charging unit to a substantially same potential as is charged by the developing unit.
The sensor outputs a detection signal indicative of an amount of toner in the image-forming unit. The controller controls a time length during which the photoconductor, charging section, and developing section are rotated, the time length being changed in accordance with the detection signal.
When the image-forming unit is nearly full of toner, the detection signal is equal to or higher than a first value and the controller sets the time length to a first time length. When the detection signal is lower than the first value, the controller sets the time length to a second time longer than the first time length.
The sensor outputs a detection signal indicative of an amount of toner in the image-forming unit. The controller controls rotational speeds at which the photoconductor, charging section, and developing section are rotated, the speeds being changed in accordance with the detection signal.
When the image-forming unit is nearly full of toner, the detection signal is equal to or higher than a first value and the controller sets the speeds to first speeds. When the detection signal is lower than the first value, the controller sets the rotational speeds to second speeds higher than the first speeds.
The detection signal indicates that the image-forming unit has been replaced, and the controller controls a time length during which the photoconductor, charging section, and developing section are rotated, the time length being changed in accordance with the detection signal.
The controller may include a wear value storing area, a lifetime value storing area, and a lifetime determining section. The wear value storing area that stores a wear value indicative of a degree of wear-out of the photoconductor. The lifetime value storing area that stores a lifetime value of the photoconductor. The lifetime determining section that compares the wear value with the lifetime value to determine whether the photoconductor has reached an end of its lifetime.
The detection signal may indicate that the image-forming unit has been replaced. The controller may control rotational speeds at which the photoconductor, charging section, and developing section are rotated, the rotational speeds being changed in accordance with the detection signal.
The controller may include a wear value storing section, a lifetime value storing area, and a lifetime determining section. The wear value storing section that stores a wear value indicative of a degree of wear-out of the photoconductor. The lifetime value storing area that stores a lifetime of the photoconductor. The lifetime determining section that compares the wear value with the lifetime value to determine whether the photoconductor has reached an end of its lifetime.
Further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.